Sheet manufacturing apparatus

ABSTRACT

A sheet manufacturing apparatus includes an impeller mill, a first sieve, a first belt, a rotary body, a second sieve, a second belt, and a heating roller. The impeller mill defibrates a raw material containing fiber and discharges a defibrated material. The first sieve screens the defibrated material by causing the defibrated material to pass through a first net. The defibrated material passing through the first sieve is deposited on the first belt to form a web. The rotary body has a protrusion radially protruded from a rotation center and divides the web by rotation to form a subdivided body. The second sieve refines the subdivided body by causing the subdivided body to pass through the second net to form a web. The refined subdivided body is deposited on the second belt to form a web. The heating roller heats the web from the second belt to form a sheet.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 15/071,356 filed on Mar. 16, 2016. This applicationclaims priority under 35 U.S.C. § 119 to Japanese Patent Application No.2015-054415, filed on Mar. 18, 2015 and Japanese Patent Application No.2016-028632, filed on Feb. 18, 2016. The entire disclosures of U.S.patent application Ser. No. 15/071,356, Japanese Patent Application No.2015-054415, and Japanese Patent Application No. 2016-028632 are herebyincorporated herein by reference.

BACKGROUND 1. Technical Field

The present invention relates to a sheet manufacturing apparatus and asheet manufacturing method.

2. Related Art

In the related art, as a sheet manufacturing apparatus, a so-calledwet-type apparatus, in which a raw material containing fiber is pouredin water, is disaggregated mainly by mechanical action, and is repulped,has been employed. In such a wet-type sheet manufacturing apparatus, alarge amount of water is required and the apparatus is increased insize. Furthermore, time and effort are taken to provide maintenance ofwater treatment facilities and energy for a drying process is largelyconsumed.

Accordingly, in order to reduce the size and save energy, a dry-typesheet manufacturing apparatus in which as little water as possible isused has been proposed. A technique is described in JP-A-2012-144819 inwhich pieces of paper are defibrated into fibers by a dry-typedefibrating machine, deinking of the fibers is performed in a cyclone,deinked fibers pass through a screen having small holes on a surface ofa forming drum and are deposited on a mesh belt, and then paper isformed.

However, in a sheet manufacturing apparatus disclosed inJP-A-2012-144819, some of the fibers are adhered to the screen havingthe small holes on the surface of the forming drum and then causeclogging. The fibers cannot pass through the small hole in whichclogging occurs and the fibers pass through the small hole in whichclogging does not occur. Thus, a defibrated material may be unlikely tobe uniformly dispersed on the mesh belt. When forming the paper in thisstate, paper having no uniform density and thickness is manufactured.

SUMMARY

An advantage of some aspects of the invention is to provide a sheetmanufacturing apparatus that can manufacture a sheet having highuniformity in density and thickness. In addition, another advantage ofsome aspects of the invention is to provide a sheet manufacturing methodthat can manufacture the sheet having high uniformity in density andthickness.

The invention can be realized in the following aspects or applicationexamples.

According to an aspect of the invention, there is provided a sheetmanufacturing apparatus including a defibrating unit configured todefibrate a raw material containing fiber into a defibrated material; ascreening unit configured to screen the defibrated material that isdefibrated by the defibrating unit; a web forming unit configured toform a web on which the defibrated material screened by the screeningunit is deposited; a dividing unit configured to divide the web formedby the web forming unit to form a subdivided body; a deposition unitconfigured to deposit the defibrated material configuring the subdividedbody; and a forming unit configured to form the sheet by pressurizingand heating the defibrated material deposited by the deposition unit.

In this case, it is possible to suppress that a plurality of thedefibrated materials are supplied to the deposition unit, for example,in a state where the plurality of the defibrated materials areaggregated into a lump shape by being entangled. Thus, it is possible tosuppress that meshes of the deposition unit are clogged. Accordingly, insuch a sheet manufacturing apparatus, it is possible to manufacture asheet having high uniformity in density and thickness.

In the sheet manufacturing apparatus, the web forming unit may have adeposition surface on which the web is deposited; and a peeling unitconfigured to peel the web deposited on the deposition surface from thedeposition surface.

In this case, it is possible to reliably peel the web from thedeposition surface.

In the sheet manufacturing apparatus, the dividing unit may include arotary body that includes a protrusion unit for forming the subdividedbody by coming into contact with the web and then dividing itself.

In this case, since the subdivided body is reliably formed by the rotarybody, it is possible to suppress that a plurality of the defibratedmaterials are supplied to the deposition unit, in a state where theplurality of the defibrated materials are entangled together and thenbecome a large lump.

In the sheet manufacturing apparatus, the web forming unit may have abelt including the deposition surface and, at least two rollers by whichthe belt is stretched, the peeling unit may have a stationary plate, andthe stationary plate may face a roller among the rollers, which ispositioned on the rotary body side, and comes into contact with thebelt.

In this case, it is possible to easily configure the peeling unit onlyby providing the stationary plate.

In the sheet manufacturing apparatus, the peeling unit may have anairflow generation unit configured to generate airflow in a direction inwhich the web is separated from the belt airflow in a direction in whichthe web is separated from the belt in the vicinity of the rotary body.

In this case, it is possible to reliably peel the web from the belt.

In the sheet manufacturing apparatus, the web forming unit may have abelt including the deposition surface. The sheet manufacturing apparatusmay further include a control unit configured to control a rotationalspeed of the rotary body in compliance with a moving speed of the meshbelt.

In this case, it is possible to reduce the variation of the volume ofthe portion of subdivided bodies supplied to the deposition unit.

The sheet manufacturing apparatus may further include a detection unitconfigured to detect a thickness of the web. The control unit maycontrol the moving speed of the belt based on the thickness of the webdetected by the detection unit.

In this case, it is possible to reduce variation of an amount of thedefibrated material per unit time supplied to the deposition unit.

The sheet manufacturing apparatus may further include a detection unitconfigured to detect a thickness of the web; and a control unitconfigured to control a rotational speed of the rotary body based on athickness of the web detected by the detection unit.

In this case, it is possible to reduce the variation of the volume ofthe portion of subdivided bodies supplied to the deposition unit.

In the sheet manufacturing apparatus, the peeling unit may have anairflow generation unit, and peel the web from the deposition surface byan airflow generated by the airflow generation unit.

In this case, it is possible to peel the web without coming into contactwith the deposition surface. Accordingly, it is possible to suppress aload to the deposition surface.

In the sheet manufacturing apparatus, the airflow generation unit mayapply an airflow to the deposition surface at an acute angle.

In this case, it is possible to efficiently peel the web from thedeposition surface.

In the sheet manufacturing apparatus, the web peeled from the depositionsurface by the airflow generated by the airflow generation unit may bedivided in a direction approximately parallel to the transportingdirection of the web.

In this case, it is possible to reduce the volume of the subdivided bodyand to easily supply (transport) the subdivided body to the depositionunit.

In the sheet manufacturing apparatus, the moisture content of theairflow applied to the deposition surface may be adjusted.

In this case, an electrostatic charge of the web is suppressed, and itis possible to easily peel the web from the deposition surface.

In the sheet manufacturing apparatus, the dividing unit may include asuction unit for forming the subdivided body by suctioning the web andthen dividing itself.

In this case, since the subdivided body is formed by suctioning the webpeeled from the deposition surface, it is possible to suppress that aplurality of the defibrated materials are supplied to the depositionunit, in a state where the plurality of the defibrated materials areentangled together and then become a large lump.

In the sheet manufacturing apparatus, the web forming unit may include abelt including the deposition surface, a supporting unit which supportsthe belt, and a rotary roller which faces the supporting unit across thebelt and the supporting unit, the web decomposed in the depositionsurface may be nipped by the supporting unit and the rotary roller, thepeeling unit may peel the web from the deposition surface by applyingthe airflow generated by the airflow generation unit to the depositionsurface, on a downstream side of the web further in a transportingdirection than the supporting unit, and the dividing unit may suctionthe web peeled by the peeling unit, by the suction unit.

In this case, it is possible to stabilize a position in which the web ispeeled from the deposition surface (peeled amount) by applying theairflow to the deposition surface in a state where the web is nipped bythe supporting unit and the rotary roller. It is possible to reducevariation of a volume of a subdivided body formed by suctioning the webpeeled from the deposition surface.

In the sheet manufacturing apparatus, an air volume caused by thesuction unit may be greater than an air volume caused by the airflowgeneration unit.

In this case, it is possible to suppress scattering or the like of thedefibrated materials caused by the airflow of the airflow generationunit.

The sheet manufacturing apparatus may further include a supply unitconfigured to supply an additive agent to the subdivided body.

In this case, it is possible to mix the defibrated material and theadditive agent with high uniformity.

In the sheet manufacturing apparatus, the web forming unit may have amesh belt on which the web is deposited; and a suction unit configuredto suction the defibrated material screened by the screening unit from asurface opposite to a surface of the mesh belt on which the web isdeposited.

In this case, it is possible to remove foreign substances such ascolorant contained in a screened material (first screened material)passing through the screening unit.

According to another aspect of the invention, there is provided a sheetmanufacturing method including defibrating a raw material containingfiber into a defibrated material; screening the defibrated material thatis defibrated; forming a web on which a screened defibrated material isdeposited; forming a subdivided body by dividing the web; depositing thedefibrated material configuring the subdivided body; and forming a sheetby pressurizing and heating a deposited defibrated material.

In such a sheet manufacturing method, it is possible to manufacture asheet having high uniformity in density and thickness.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a view schematically illustrating a sheet manufacturingapparatus according to a first embodiment.

FIG. 2 is a view schematically illustrating the sheet manufacturingapparatus according to the first embodiment.

FIG. 3 is a flowchart describing a process of a control unit of thesheet manufacturing apparatus according to the first embodiment.

FIG. 4 is a flowchart describing the process of the control unit of thesheet manufacturing apparatus according to the first embodiment.

FIG. 5 is a view schematically illustrating a sheet manufacturingapparatus according to a modification example of the first embodiment.

FIG. 6 is a view schematically illustrating a sheet manufacturingapparatus according to a second embodiment.

FIG. 7 is a view schematically illustrating the sheet manufacturingapparatus according to the second embodiment.

FIG. 8 is a view schematically illustrating a sheet manufacturingapparatus according to a first modification example of the secondembodiment.

FIG. 9 is a view schematically illustrating a sheet manufacturingapparatus according to a second modification example of the secondembodiment.

FIG. 10 is a view schematically illustrating the sheet manufacturingapparatus according to a third embodiment.

FIG. 11 is a view schematically illustrating the sheet manufacturingapparatus according to the third embodiment.

FIG. 12 is a view schematically illustrating a blowing unit of anairflow generation unit according to the third embodiment.

FIG. 13 is a view schematically illustrating an example of other shapeof the blowing unit of an airflow generation unit according to the thirdembodiment.

FIG. 14 is a view schematically illustrating an example of other shapeof the blowing unit of an airflow generation unit according to the thirdembodiment.

FIG. 15 is a view schematically illustrating a suction port unit of adividing unit according to the third embodiment.

FIG. 16 is a view schematically illustrating an example of other shapeof the suction port unit of a dividing unit according to the thirdembodiment.

FIG. 17 is a view schematically illustrating an example of other shapeof the suction port unit of a dividing unit according to the thirdembodiment.

FIG. 18 is a view schematically illustrating the sheet manufacturingapparatus according to a fourth embodiment.

FIG. 19 is a view schematically illustrating a rotary body according tothe fourth embodiment.

FIG. 20 is a view schematically illustrating an example of other shapeof the rotary body according to the fourth embodiment.

FIG. 21 is a view schematically illustrating an example of other shapeof the rotary body according to the fourth embodiment.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, a preferred embodiment of the invention will be describedin detail with reference to the drawings. Moreover, the embodimentsdescribed below do not unduly limit contents of the invention describedin the claims. In addition, not all of the elements that are describedare essential requirements of the invention.

1. First Embodiment

1.1. Sheet Manufacturing Apparatus

1.1.1. Configuration

First, a sheet manufacturing apparatus according to a first embodimentwill be described with reference to the drawings. FIG. 1 is a viewschematically illustrating a sheet manufacturing apparatus 100 accordingto the first embodiment.

As illustrated in FIG. 1, the sheet manufacturing apparatus 100 includesa supply unit 10, a manufacturing unit 102, and a control unit 140. Themanufacturing unit 102 manufactures a sheet. The manufacturing unit 102has a crushing unit 12, a defibrating unit 20, a screening unit 40, afirst web forming unit 45 (web forming unit), a mixing unit 50, adeposition unit 60, a second web forming unit 70, a sheet forming unit80 (forming unit), and a cutting unit 90.

The supply unit 10 supplies a raw material to the crushing unit 12. Thesupply unit 10 is, for example, an automatic feeding unit forcontinuously feeding the raw material into the crushing unit 12. The rawmaterial supplied by the supply unit 10 contains, for example, fibersuch as waste paper and a pulp sheet.

The crushing unit 12 cuts the raw material supplied by the supply unit10 into small pieces in the air. Shapes and sizes of the small piecesare, for example, several cm squares. In the illustrated example, thecrushing unit 12 has crushing blades 14 and it is possible to cut thefed raw material by the crushing blades 14. As the crushing unit 12, forexample, a shredder is used. The raw material that is cut by thecrushing unit 12 is transported (transferred) to the defibrating unit 20via a pipe 2 after being received from a hopper 1.

The defibrating unit 20 defibrates the raw material that is cut by thecrushing unit 12. Here, “defibrating” refers to that the raw material(defibration object) formed by binding a plurality of fibers isuntangled to the fibers one by one. The defibrating unit 20 also has afunction of separating a material such as resin particles, ink, toner,and a blur-preventing agent adhering to the raw material from the fiber.

The “defibrated material” is referred to as one passing through thedefibrating unit 20. The “defibrated material” may include resin (resinfor bonding a plurality of fibers to each other) particles, colorantsuch as ink and toner, a blur-preventing agent, and additives such aspaper strength enhancer which are separated from the fibers when thefibers are untangled in addition to the untangled defibrated materialfiber. The shape of the defibrated material that is untangled is astring shape or a ribbon shape. The defibrated material that isuntangled may be present in a state (independent stat) of not beingentangled with other untangled fibers, or may be present in a state(state of forming a so-called “lump”) of being lump-shaped by beingentangled with other untangled defibrated material.

The defibrating unit 20 performs defibrating in the dry-type in theatmosphere (in the air). Specifically, as the defibrating unit 20, animpeller mill is used. The defibrating unit 20 has a function ofsuctioning the raw material and generating airflow to discharge thedefibrated material. Thus, the defibrating unit 20 suctions the rawmaterial from an inlet 22 by the airflow generated by the defibratingunit 20 together with the airflow, performs defibrating process, and cantransport the defibrated material to an outlet 24. The defibratedmaterial passing through the defibrating unit 20 is transferred to thescreening unit 40 via a pipe 3.

The screening unit 40 feeds the defibrated material that is defibratedby the defibrating unit 20 from the inlet 42 and screens the defibratedmaterial by a length of the fiber. As the screening unit 40, forexample, a sieve (screen) is used. The screening unit 40 has a net(filter and screen) and can separate the fibers or particles (onepassing through the net and a first screened material) that are smallerthan meshes of the net in size and the fibers, non-defibrated pieces, orlump (one that does not pass through the net and a second screenedmaterial) that are larger than the meshes of the net in size. Forexample, the first screened material is fed to the mixing unit 50 via apipe 7. The second screened material is returned from the outlet 44 tothe defibrating unit 20 via a pipe 8. Specifically, the screening unit40 is a cylindrical sieve that can be rotated by a motor. As the net ofthe screening unit 40, for example, a metal net, expanded metal that isformed by extending a metal plate in which cut lines are run, and aperforated metal in which holes are formed in a metal plate by a pressmachine are used.

The first web forming unit 45 transports the first screened materialpassing through the screening unit 40 to the mixing unit 50. The firstweb forming unit 45 includes a mesh belt 46 which is used as a beltincluding a deposition surface, tension rollers 47, and a suction unit(suction mechanism) 48.

The suction unit 48 is able to suction the first screened materialpassing through openings (openings of the net) of the screening unit 40and being dispersed in the air on the mesh belt 46. The first screenedmaterial is deposited on the moving mesh belt 46 and forms a web V.Basic configurations of the mesh belt 46, the tension rollers 47, andthe suction unit 48 are similar to a mesh belt 72, tension rollers 74,and a suction mechanism 76 of the second web forming unit 70 describedbelow.

The web V is formed in a soft and inflated state rich in air by goingthrough the screening unit 40 and the first web forming unit 45. The webV that is deposited on the mesh belt 46 is fed into the pipe 7 and istransported to the mixing unit 50.

The mixing unit 50 mixes the first screened material (first screenedmaterial transported by the first web forming unit 45) passing throughthe screening unit 40 and the additive agent containing the fiber. Themixing unit 50 has an additive agent supply unit 52 (supply unit) whichsupplies an additive agent, a pipe 54 transporting the first screenedmaterial and the additive agent, and a blower 56. In an illustratedexample, the additive agent is supplied from the additive agent supplyunit 52 to the pipe 54 via a hopper 9. The pipe 54 is continuous withthe pipe 7.

In the mixing unit 50, airflow is generated by the blower 56 and in thepipe 54, the first screened material and the additive agent can betransported while being mixed. Moreover, a mechanism for mixing thefirst screened material and the additive agent is not specificallylimited and may be one that stirs the first screened material and theadditive agent by blades at a high speed or may use rotation of acontainer such as a V-type mixer.

As the additive agent supply unit 52, a screw feeder illustrated in FIG.1, a disk feeder (not illustrated), or the like is used. The additiveagent supplied from the additive agent supply unit 52 contains resin forbonding a plurality of the fibers. The plurality of the fibers are notbonded at the time of supplying the resin. The resin is melted whenpassing through the sheet forming unit 80 and the plurality of thefibers are bonded.

The resin supplied from the additive agent supply unit 52 isthermoplastic resin or thermosetting resin, and includes, for example,AS resin, ABS resin, polypropylene, polyethylene, polyvinyl chloride,polystyrene, acrylic resin, polyester resin, polyethylene terephthalate,polyphenylene ether, polybutylene terephthalate, nylon, polyamide,polycarbonate, polyacetal, polyphenylene sulfide, polyether etherketone, and the like. Those resins may be used singly or may be used bybeing appropriately mixed. The additive agent supplied from the additiveagent supply unit 52 may be fibrous or may be powder.

Colorant for coloring the fibers, aggregation preventing materialinhibitor for preventing aggregation of the fibers, and flame retardantfor the fibers and the like making it difficult to burn may be containedin the additive agent supplied from the additive agent supply unit 52depending on the type of the manufactured sheet in addition to the resinfor bonding the fibers. The mixture (mixture of the first screenedmaterial and the additive agent) passing through the mixing unit 50 istransferred to the deposition unit 60 via the pipe 54.

The deposition unit 60 introduces the mixture passing through the mixingunit 50 from an inlet 62, refines the entangled defibrated material(fibers), and causes the defibrated material to fall while dispersingthe defibrated material. Furthermore, if the resin of the additive agentsupplied from the additive agent supply unit 52 is fibrous, thedeposition unit 60 refines the entangled resin. Thus, the depositionunit 60 can uniformly deposit the mixture on the second web forming unit70.

As the deposition unit 60, a rotating cylindrical sieve is used. Thedeposition unit 60 has a net and causes the resin or particles (passingthrough the net) smaller than meshes of the net in size contained in themixture passing through the mixing unit 50 to fall. A configuration ofthe deposition unit 60 is, for example, the same as the configuration ofthe screening unit 40.

Moreover, the “sieve” of the deposition unit 60 may not have a functionfor screening a specific object. That is, the “sieve” used as thedeposition unit 60 means to have the net and the deposition unit 60possibly cause all the mixtures introduced into the deposition unit 60to fall.

The second web forming unit 70 forms a web W by depositing apassing-through material passing through the deposition unit 60. Thesecond web forming unit 70 has, for example, the mesh belt 72, thetension rollers 74, and the suction mechanism 76.

The mesh belt 72 deposits the passing-through material passing throughthe openings (openings of the net) of the deposition unit 60 whilemoving. The mesh belt 72 is stretched by the tension rollers 74 and isconfigured such that air is unlikely to pass through the passing-throughmaterial. The mesh belt 72 is moved by rotation of the tension rollers74. The passing-through material passing through the deposition unit 60continuously falls and deposits while the mesh belt 72 is continuouslymoved. Thus, the web W is formed on the mesh belt 72. The mesh belt 72is, for example, made of metal, resin, fabric, non-woven fabric, and thelike.

The suction mechanism 76 is provided below (side opposite to thedeposition unit 60 side) the mesh belt 72. The suction mechanism 76 cangenerate airflow (airflow from the deposition unit 60 to the mesh belt72) downward. It is possible to suction the mixture, which is dispersedin the air by the deposition unit 60, on the mesh belt 72 by the suctionmechanism 76. Thus, it is possible to increase a discharge speed fromthe deposition unit 60. Furthermore, it is possible to form a down-bowin a fall path of the mixture and to prevent the defibrated material andthe additive agent to be entangled during falling by the suctionmechanism 76.

As described above, the web W is formed in a soft and inflated staterich in air by going through the deposition unit 60 and the second webforming unit 70 (web forming process). The web W deposited in the meshbelt 72 is transported to the sheet forming unit 80.

Moreover, in the illustrated example, a moisture-adjusting unit 78 thatadjusts moisture of the web w is provided. The moisture-adjusting unit78 can adjust an amount ratio of the web W and water by adding water orsteam to the web W.

The sheet forming unit 80 forms a sheet S by pressurizing and heatingthe web W deposited on the mesh belt 72. In the sheet forming unit 80,it is possible to bond the plurality of the fibers together in themixture via the additive agent (resin) by heating the defibratedmaterial and the mixture of the additive agent mixed in the web W.

As the sheet forming unit 80, for example, a heating roller (heaterroller), a heat press molding machine, a hot plate, a hot air blower, aninfrared heater, and a flash fixing machine are used. In the illustratedexample, the sheet forming unit 80 includes a first bonding unit 82 anda second bonding unit 84, and the bonding units 82 and 84 respectivelyinclude a pair of heating rollers 86. By configuring the bonding units82 and 84 as the heating rollers 86, it is possible to form the sheet Swhile continuously transporting the web W by configuring the bondingunits 82 and 84 as the heating rollers 86 compared to a case where thebonding units 82 and 84 are configured as a flat press device (platepress device). Moreover, the number of the heating rollers 86 is notspecifically limited.

The cutting unit 90 cuts the sheet S formed by the sheet forming unit80. In the illustrated example, the cutting unit 90 has a first cuttingunit 92 that cuts the sheet S in a direction intersecting a transportingdirection of the sheet S and a second cutting unit 94 that cuts thesheet S in a direction parallel to the transporting direction. Thesecond cutting unit 94 cuts, for example, the sheet S passing throughthe first cutting unit 92.

As described above, the cutform-shaped sheet S having a predeterminedsize is formed. The cutform-shaped sheet S that is cut is discharged toa discharge unit 96.

1.1.2. Rotary Body (Dividing Unit) and Detection Unit

The sheet manufacturing apparatus 100 further includes a dividing unit180. The dividing unit 180 divides the web V formed by the first webforming unit 45 to form the subdivided bodies 11. The dividing unit 180according to the present embodiment has a rotary body 110. Here, FIG. 2is an enlarged view of a region including the rotary body 110 of FIG. 1schematically illustrating the sheet manufacturing apparatus 100.Furthermore, a functional block view of the control unit 140 of thesheet manufacturing apparatus 100 is illustrated in FIG. 2.

The suction unit 48 of the first web forming unit 45 suctions thedefibrated material screened by the screening unit 40 from a surfaceopposite to the surface of the mesh belt 46 on which the web V isdeposited and the first web forming unit 45 forms the web V on which thedefibrated material screened by the screening unit 40 is deposited.Then, as illustrated in FIG. 2, the rotary body 110 forms subdividedbodies 11 by dividing (cutting or shearing) the web V formed by thefirst web forming unit 45.

The rotary body 110 has a base unit 112 and a protrusion unit 114protruding from the base unit 112. The protrusion unit 114 has, forexample, a planar shape. In the illustrated example, four protrusionunits 114 are provided and the four protrusion units 114 are provided atequal intervals. Moreover, although not illustrated, the number of theprotrusion units 114 is not specifically limited and may be, forexample, two. In addition, a shape of the protrusion unit 114 is notspecifically limited.

The rotary body 110 can rotate in an arrow direction R1. Specifically,the base unit 112 rotates in the arrow direction R1 and thereby theprotrusion units 114 can rotate around the base unit 112. The tensionrollers 47 of the first web forming unit 45 can rotate in an arrowdirection R2. A rotating direction of the rotary body 110 and a rotatingdirection of the tension roller 47 are opposite to each other. Arotational speed of the rotary body 110 is greater than a rotationalspeed of the tension roller 47. The peripheral speed of the rotary body110 (speed of the tip end of the protrusion unit 114) is greater thanthe moving speed of the mesh belt 46 (transporting speed of the web V).For example, in a case where the moving speed of the mesh belt 46 is setin a range of 20 mm to 100 mm per second, the peripheral speed of therotary body 110 is set to a speed which is five or more times the movingspeed of the mesh belt 46.

The rotary body 110 is provided in the vicinity of the first web formingunit 45. In the illustrated example, the rotary body 110 is provided inthe vicinity of a tension roller 47 a positioned on a downstream side ina path of the web V. More specifically, the rotary body 110 is providednext (position separated from the tension roller 47 a on a downstreamside (mixing unit 50 side) in a horizontal direction) to the tensionroller 47 a. The rotary body 110 is provided in a position in which theprotrusion units 114 can come into contact with the web V and does notcome into contact with the mesh belt 46 on which the web V is deposited.Thus, it is possible to suppress that the mesh belt 46 is worn (damaged)by the protrusion units 114. The shortest distance between theprotrusion unit 114 and the mesh belt 46 is, for example, equal to orgreater than 0.05 mm and equal to or less than 0.5 mm, and is preferably0.1 mm.

A thickness (length in the rotating direction) of the protrusion unit114 is, for example, equal to or greater than 0.1 mm and equal to orless than 3 mm and is preferably 0.8 mm. In addition, a width (length ina direction of a rotational axis) of the protrusion unit 114 isappropriately determined in compliance with the width (length in adirection orthogonal to the transporting direction of the web V) of theweb V. In addition, the length (length in a direction orthogonal to therotational axis) of the protrusion unit 114 is appropriately determinedin compliance with a positional relationship between the rotary body 110and the web V (mesh belt 46 or the tension roller 47 a).

The web V is divided and becomes the subdivided body 11 by theprotrusion units 114 of the rotary body 110 and is introduced into themixing unit 50 via the pipe 7 by, for example, its own weight or airflowgenerated in the mixing unit 50. The additive agent supply unit 52 ofthe mixing unit 50 supplies the additive agent to the subdivided body11. A size or a shape of the subdivided body 11 is not specificallylimited and a volume of the subdivided body 11 is, for example, equal toor greater than 5 mm³ and equal to or less than 25000 mm³.

The deposition unit 60 deposits the defibrated material configuring thesubdivided body 11. Specifically, the deposition unit 60 refines thesubdivided body 11 and deposits the refined subdivided body 11(defibrated material configuring the subdivided body 11) on the meshbelt 72. Then, the sheet forming unit 80 forms the sheet S bypressurizing and heating the defibrated material that is deposited bythe deposition unit 60.

The sheet manufacturing apparatus 100 further has a detection unit 120.The detection unit 120 detects a thickness of the web V deposited on themesh belt 46. The detection unit 120 is, for example, an optical sensorthat receives reflected light in a front surface and reflected light ina rear surface of the web V and detects the thickness of the web V basedon a time difference between the reflected light in the front surfaceand the reflected light in the rear surface. The detection unit 120faces, for example, the mesh belt 46. Moreover, a shape of the detectionunit 120 is not specifically limited as long as the thickness of the webV can be detected.

Moreover, in the illustrated example, the sheet manufacturing apparatus100 has a housing unit 40 a accommodating the screening unit 40 and apile seal 40 b provided in the housing unit 40 a. The pile seal 40 b isconfigured of, for example, a brush in which fine hairs are denselyimplanted on a surface of a base unit and the brush comes into contactwith the mesh belt 46. The pile seal 40 b can suppress that thedefibrated material screened by the screening unit 40 is leaked from agap between the housing unit 40 a and the mesh belt 46.

1.1.3. Control Unit

As illustrated in FIG. 2, the control unit 140 of the sheetmanufacturing apparatus 100 has an operation unit 141, an output unit142, a storage unit 143, a storage medium 144, and a processing unit145.

The operation unit 141 acquires an operation signal in compliance withan operation of a user and performs a transferring process of the signalto the processing unit 145. The operation unit 141 is, for example,buttons, keys, a touch panel type display, a mouse, and the like.

The output unit 142 displays a processing result of the processing unit145 based on the signal input from the processing unit 145. The outputunit 142 displays, for example, the processing result of the processingunit 145 with letters. The output unit 142 is, for example, a liquidcrystal display (LCD), a cathode ray tube (CRT), a touch panel typedisplay, and the like. Moreover, the output unit 142 may output theprocessing result of the processing unit 145 by sound.

The storage unit 143 stores programs and data for performing variouscontrol processes by the processing unit 145. The storage unit 143 isfurther used as an operation region of the processing unit 145 andtemporarily stores operation signals input from the operation unit 141,programs and data read from the storage medium 144 and the like, acalculation result executed by the processing unit 145 in accordancewith various programs, and the like.

The storage medium 144 is a computer-readable storage medium for storingvarious application programs and data. Moreover, the programs may bedistributed in the storage medium 144 (storage unit 143) from aninformation storage medium included in a host device (server) via anetwork. The storage medium 144 may also function as a storage unit thatstores data that is necessary for being stored for a long period of timeamong data generated by the process of the processing unit 145. Thestorage medium 144 is realized by, for example, an optical disk (CD andDVD), magneto-optical disk (MO), a magnetic disk, a hard disk, amagnetic tape, and a memory (ROM, a flash memory, and the like).

The processing unit 145 performs various processes in compliance withprograms stored in the storage unit 143 or programs stored in thestorage medium 144. Specifically, the processing unit 145 performs thefollowing process. The function of the processing unit 145 can berealized by various processors (CPU, DSP, and the like), hardware suchas a gate array (ASIC), and programs. Moreover, at least a part of theprocessing unit 145 may be realized by hardware (dedicated circuit).

Here, FIG. 3 is a flowchart describing the process of the control unit140.

For example, when the user requests a process via the operation unit141, the processing unit 145 receives an operation signal from theoperation unit 141 and starts the process.

First, the processing unit 145 receives a signal from the detection unit120 and acquires the thickness of the web V detected by the detectionunit 120 (S1). The processing unit 145 may perform a process ofdisplaying the acquired thickness of the web V on the output unit 142.

Next, the processing unit 145 controls the moving speed of the mesh belt46 based on the thickness of the web V detected by the detection unit120 (S2). Specifically, the processing unit 145 receives a signal fromthe detection unit 120, outputs the signal to a first driving unit(driving unit for driving the tension roller 47) (not illustrated), andcontrols the rotational speed of the tension roller 47.

If the thickness of the web V detected by the detection unit 120 is, forexample, greater than a predetermined value, the processing unit 145 iscontrolled such that the moving speed of the mesh belt 46 is decreased.Thus, it is possible to suppress that an amount of the defibratedmaterial per unit time supplied to the mixing unit 50 is increased. Inaddition, for example, if the thickness of the web V detected by thedetection unit 120 is, for example, less than a predetermined value, theprocessing unit 145 is controlled such that the moving speed of the meshbelt 46 is increased. Thus, it is possible to suppress that the amountof the defibrated material per unit time supplied to the mixing unit 50is decreased. That is, the processing unit 145 controls the moving speedof the mesh belt 46 such that variation of the amount (mass) of thedefibrated material per unit time supplied to the mixing unit 50 isreduced.

Next, the processing unit 145 controls the rotational speed (number ofrotations) of the rotary body 110 in compliance with the moving speed ofthe mesh belt 46 (based on the moving speed) (S3). Specifically, theprocessing unit 145 outputs a signal to a second driving unit (drivingunit for driving the rotary body 110) (not illustrated) after outputtinga signal to the first driving unit and controls the number of rotationsof the rotary body 110. For example, the moving speed of the mesh belt46 and data regarding the number of rotations of the rotary body 110 arestored in the storage unit 143 in advance and the processing unit 145may output a signal to the second driving unit by acquiring informationregarding the number of rotations of the rotary body 110 based on thedata.

For example, in step S2, if control of the mesh belt 46 is performedsuch that the moving speed of the mesh belt 46 is decreased, theprocessing unit 145 is controlled such that the number of rotations ofthe rotary body 110 is decreased. Thus, it is possible to suppress thata volume of the subdivided body supplied 11 to the mixing unit 50 isreduced. In addition, for example, in step S2, if the control isperformed such that the moving speed of the mesh belt 46 is increased,the processing unit 145 is controlled such that the number of rotationsof the rotary body 110 is increased. Thus, it is possible to suppressthat the volume of the subdivided body 11 supplied to the mixing unit 50is increased. That is, the processing unit 145 controls the number ofrotations of the rotary body 110 such that variation of the volume ofthe subdivided body 11 supplied to the mixing unit 50 is reduced.

Moreover, the sheet manufacturing apparatus 100 has a detection unit(not illustrated) detecting the moving speed of the mesh belt 46 and theprocessing unit 145 may control the number of rotations of the rotarybody 110 based on the moving speed of the mesh belt 46 detected by thedetection unit.

The processing unit 145 controls, for example, the number of rotationsof the rotary body 110 (signal is output to the second driving unit) andthen completes the process.

Moreover, as illustrated in FIG. 4, the processing unit 145 may controlthe number of rotations of the rotary body 110 based on the thickness ofthe web V detected by the detection unit 120 after step S1 (S4).Specifically, the processing unit 145 outputs a signal to the seconddriving unit (not illustrated) by receiving the signal from thedetection unit 120 and may control the number of rotations of the rotarybody 110.

For example, if the thickness of the web V detected by the detectionunit 120 is greater than a predetermined value, the processing unit 145may be controlled such that the number of rotations of the rotary body110 is increased. Thus, it is possible to suppress that the volume ofthe subdivided body 11 supplied to the mixing unit 50 is increased. Inaddition, for example, if the thickness of the web V detected by thedetection unit 120 is less than the predetermined value, the processingunit 145 may be controlled such that the number of rotations of therotary body 110 is decreased. Thus, it is possible to suppress that thevolume of the subdivided body 11 supplied to the mixing unit 50 isdecreased.

The sheet manufacturing apparatus 100 has, for example, the followingcharacteristics.

The sheet manufacturing apparatus 100 has the first web forming unit 45that forms the web V on which the defibrated material screened by thescreening unit 40 is formed and the rotary body 110 that includes theprotrusion units 114 for forming the subdivided body 11 by dividing theweb V formed by the first web forming unit 45. Thus, in the sheetmanufacturing apparatus 100, for example, it is possible to reduce thevariation of the amount of the defibrated material per unit timesupplied to the deposition unit 60. Furthermore, for example, it ispossible to reduce the variation of the volume of the subdivided body 11supplied to the deposition unit 60. Thus, in the sheet manufacturingapparatus 100, it is possible to suppress that the plurality of thedefibrated materials are supplied to the deposition unit 60 in a statewhere the plurality of the defibrated materials are entangled togetherand then become a large lump and to suppress that meshes of thedeposition unit 60 are clogged. Thus, in the sheet manufacturingapparatus 100, it is possible to manufacture the sheet S having highuniformity in density and thickness.

Furthermore, since the sheet manufacturing apparatus 100 includes thefirst web forming unit 45, it is possible to further reduce thevariation of the amount of the defibrated material per unit timesupplied to the deposition unit 60. For example, the defibrated materialis adhered on an inner wall of the pipe 3 connecting the defibratingunit 20 and the screening unit 40 and then even if the amount of thedefibrated material per unit time supplied to the screening unit 40 isvaried, it is possible to transport the defibrated material to thedeposition unit 60 in a state where variation of the amount of thedefibrated material is reduced by depositing the defibrated material onthe mesh belt 46 of the first web forming unit 45.

In the sheet manufacturing apparatus 100, the control unit 140 controlsthe rotational speed of the rotary body 110 in compliance with themoving speed of the mesh belt 46. Thus, in the sheet manufacturingapparatus 100, it is possible to reduce the variation of the volume ofthe subdivided body 11 supplied to the deposition unit 60.

In the sheet manufacturing apparatus 100, the control unit 140 controlsthe moving speed of the mesh belt 46 based on the thickness of the web Vdetected by the detection unit 120. Thus, in the sheet manufacturingapparatus 100, it is possible to reduce the variation of the amount ofthe defibrated material per unit time supplied to the deposition unit60.

In the sheet manufacturing apparatus 100, the control unit 140 maycontrol the rotational speed of the rotary body 110 based on thethickness of the web V detected by the detection unit 120. Thus, in thesheet manufacturing apparatus 100, it is possible to reduce thevariation of the volume of the subdivided body 11 supplied to thedeposition unit 60.

The sheet manufacturing apparatus 100 has the additive agent supply unit52 that supplies the additive agent to the subdivided body 11. Thus, inthe sheet manufacturing apparatus 100, it is possible to uniformly mixthe defibrated material and the additive agent. For example, even if theadditive agent is supplied to the web V in a state where the web V isnot divided, the defibrated material and the additive agent may not beuniformly mixed. Furthermore, in the sheet manufacturing apparatus 100,since it is possible to reduce the variation of the amount of thedefibrated material per unit time supplied to the mixing unit 50, forexample, it is possible to reduce a time when the defibrated material isnot present in the mixing unit 50. Thus, for example, if the additiveagent is continuously supplied from the additive agent supply unit 52,it is possible to decrease the amount of the additive agent that is notmixed into the defibrated material and to suppress that the additiveagent is wasted. Thus, for example, it is possible to reduce the cost.

The sheet manufacturing apparatus 100 has the suction unit 48 thatsuctions the defibrated material screened by the screening unit 40.Thus, in the sheet manufacturing apparatus 100, it is possible to removethe foreign matter such as colorant contained in the first screenedmaterial passing through the screening unit 40.

In the sheet manufacturing apparatus 100, the protrusion unit 114 has aplanar shape. Thus, even if the protrusion unit 114 comes into contactwith the mesh belt 46, it is possible to reduce a possibility ofdamaging the mesh belt 46. For example, if a shape of a tip of theprotrusion unit is a sharp blade-shaped, it is possible to increase thepossibility of damaging the mesh belt when the protrusion unit comesinto contact with the mesh belt.

In a sheet manufacturing method according to the embodiment, forexample, the sheet manufacturing apparatus 100 is used. The sheetmanufacturing method using the sheet manufacturing apparatus 100, asdescribed above includes a step of defibrating the raw materialcontaining the fibers into the defibrated material, a step of screeningthe defibrated material that is defibrated, a step of forming the web Von which the screened defibrated material is deposited, a step offorming the subdivided body 11 by dividing the web V, a step ofdepositing the defibrated material configuring the subdivided body 11,and a step of forming the sheet by pressurizing and heating thedefibrated material that is deposited. Thus, in the sheet manufacturingmethod using the sheet manufacturing apparatus 100, it is possible tomanufacture the sheet S having high uniformity in density and thickness.

1.2. Modification Example of Sheet Manufacturing Apparatus

Next, a sheet manufacturing apparatus of a modification example of thefirst embodiment will be described with reference to the drawings. FIG.5 is a view schematically illustrating a sheet manufacturing apparatus200 according to the modification example of the first embodiment.Hereinafter, in the sheet manufacturing apparatus 200, points differentfrom the example of the above-described sheet manufacturing apparatus100 will be described and description of the same points will beomitted.

As illustrated in FIG. 5, the sheet manufacturing apparatus 200 isdifferent from the sheet manufacturing apparatus 100 described above inthat a classifying unit 30 is provided. In the sheet manufacturingapparatus 200, the defibrated material passing through a defibratingunit 20 is fed to the classifying unit 30 via a pipe 3.

The classifying unit 30 classifies the defibrated material passingthrough the defibrating unit 20. Specifically, the classifying unit 30classifies and removes a defibrated material (resin particles, colorant,additive agent, and the like) having a relatively small size and lowdensity among the defibrated materials. Thus, it is possible to increasea proportion of the fibers having a relatively large size and highdensity among the defibrated materials.

As the classifying unit 30, an airflow type classifier is used. Theairflow type classifier generates a whirling air current, separates thedefibrated materials by a difference in centrifugal force received bythe size and density of the defibrated materials that are classified,and can adjust classification points by adjusting a speed of airflow andthe centrifugal force. Specifically, as the classifying unit 30,cyclone, elbow jet, eddy classifier, and the like are used.Particularly, since the cyclone is simple in structure as illustrated inthe view, it is possible to appropriately use the cyclone as theclassifying unit 30.

The classifying unit 30 has, for example, an inlet 31, a cylindricalunit 32 that is connected to the inlet 31, an inverse cone unit 33 thatis positioned below the cylindrical unit 32 and is connected to thecylindrical unit 32, a lower outlet 34 that is provided in a lowercenter of the inverse cone unit 33, and an upper outlet 35 that isprovided in an upper center of the cylindrical unit 32.

In the classifying unit 30, the airflow carrying the defibrated materialintroduced from the inlet 31 is changed into a circumferential movementby the cylindrical unit 32. Thus, the centrifugal force is applied tothe introduced defibrated material and the classifying unit 30 separatesthe defibrated material into fiber (first classified material) of whichthe size and density are higher than resin particles or ink particlesamong the defibrated materials and the resin particles, colorant, theadditive agent, and the like (second classified material) of which thesize and density are lower than the fiber among the defibratedmaterials. The first classified material is discharged from the loweroutlet 34 and is introduced into the screening unit 40 via a pipe 4. Onthe other hand, the second classified material is discharged from theupper outlet 35 to a receiving unit 36 via a pipe 5.

The sheet manufacturing apparatus 200 has the classifying unit 30. Thus,the defibrated material passing through the defibrating unit 20 can beseparated into the first classified material and the second classifiedmaterial.

2. Second Embodiment

2.1. Sheet Manufacturing Apparatus

Next, a sheet manufacturing apparatus according to a second embodimentwill be described with reference to the drawings. FIG. 6 is a viewschematically illustrating a sheet manufacturing apparatus 300 accordingto the second embodiment and is an enlarged view of a region including arotary body 110. Hereinafter, in the sheet manufacturing apparatus 300,points different from the example of the above-described sheetmanufacturing apparatus 100 will be described and description of thesame points will be omitted.

As illustrated in FIG. 6, the sheet manufacturing apparatus 300 isdifferent from the above-described sheet manufacturing apparatus 100 inthat a peeling unit 310 is provided. The peeling unit 310 is a memberfor peeling a web V deposited on a mesh belt 46 from a mesh belt 46.

The peeling unit 310 has a stationary plate 312. Here, FIG. 7 is anenlarged view of a region including the stationary plate 312 of FIG. 6.In the illustrated example, the peeling unit 310 is configured of thestationary plate 312. The stationary plate 312 is provided in thevicinity of (adjacent to) a rotary body 110. In the example illustratedin FIG. 6, a first web forming unit 45 has three tension rollers 47 onwhich a mesh belt 46 is stretched and the stationary plate 312 faces atension roller 47 a positioned on the nearest side to the rotary body110 among three tension rollers via the mesh belt 46. The stationaryplate 312 comes into contact with the mesh belt 46 in a state where themesh belt 46 is able to be moved. The stationary plate 312 is fixedwithout moving with the movement of the mesh belt 46.

The stationary plate 312 has, for example, a planar shape. Thestationary plate 312 comes into contact with the mesh belt 46 in a mainsurface 313. A thickness of the stationary plate 312 is, for example,equal to or greater than 0.05 mm and equal to or less than 1 mm, and ispreferably 0.2 mm. The stationary plate 312 is able to come into contactwith the web V at an end 314.

In FIG. 7, an angle θ formed by a tangent T of a curve that is formed bythe mesh belt 46 and a straight line that is formed by the main surface313 of the stationary plate 312 in a contact point between thestationary plate 312 and the mesh belt 46 is greater than 0° and equalto or less than 45° and preferably is greater than 0° and equal to orless than 20°.

A base unit 112 of the rotary body 110 is provided below (lower side ina vertical direction) the end 314 of the stationary plate 312. Thus, inthe sheet manufacturing apparatus 300, a part of the web V is peeledfrom the mesh belt 46 by the end 314 of the stationary plate 312 and itis possible to divide the peeled web V by a protrusion unit 114 of therotary body 110.

The sheet manufacturing apparatus 300 has the peeling unit 310 forpeeling the web V from the mesh belt 46. Thus, in the sheetmanufacturing apparatus 300, it is possible to reliably peel the web Vfrom the mesh belt 46. Specifically, in the sheet manufacturingapparatus 300, the peeling unit 310 has the stationary plate 312. Thus,it is possible to easily configure the peeling unit 310 only byproviding the stationary plate 312.

2.2. Modification Example of Sheet Manufacturing Apparatus

2.2.1. First Modification Example

Next, a sheet manufacturing apparatus according to a first modificationexample of the second embodiment will be described with reference to thedrawings. FIG. 8 is a view schematically illustrating a sheetmanufacturing apparatus 400 according to the first modification exampleof the second embodiment. Hereinafter, in the sheet manufacturingapparatus 400, points different from the examples of the above-describedsheet manufacturing apparatuses 100 and 300 will be described anddescription of the same points will be omitted.

As illustrated in FIG. 8, the sheet manufacturing apparatus 400 isdifferent from the above-described sheet manufacturing apparatus 300 inthat a moisture-adjusting unit 478 for adjusting the moisture content ofthe web V is provided. The moisture-adjusting unit 478 can adjust anamount ratio of the web V and water by adding water or steam to the webV. In the illustrated example, a detection unit 120 is provided in aposition in which a thickness of the web V can be detected before addingwater and the like to the web V by the moisture-adjusting unit 478, butthe detection unit 120 may be provided in a position in which thethickness of the web V can be detected after adding water and the liketo the web V by the moisture-adjusting unit 478.

In the sheet manufacturing apparatus 400, a cover unit 440 is providedso as to cover the web V transported to the outside of a housing unit 40a. For example, two openings are provided, the detection unit 120 isprovided in one opening, and the moisture-adjusting unit 478 is providedin the other opening in the cover unit 440. The cover unit 440 and apipe 7 are connected by a pile seal 442. Thus, it is possible tosuppress that moisture is leaked from the moisture-adjusting unit 478 tothe outside. A configuration of the pile seal 442 is, for example, thesame as that of the pile seal 40 b.

A peeling unit 310 of the sheet manufacturing apparatus 400 further hasa stationary plate 412. The stationary plate 412 is provided above(upper side in the vertical direction) a rotary body 110. In theillustrated example, the stationary plate 412 comes into contact withthe pile seal 442. A size and shape of the stationary plate 412 is, forexample, the same as those of the stationary plate 312. For example, ifthe web V is moved along the pile seal 442, the stationary plate 412 canpeel the web V from the pile seal 442. The web V that is peeled by thestationary plate 412 is divided by a protrusion unit 114 of the rotarybody 110 when passing between the rotary body 110 and a tension roller47 a.

The sheet manufacturing apparatus 400 has the moisture-adjusting unit478. Thus, it is possible to adjust moisture of the web V. Furthermore,the sheet manufacturing apparatus 400 has the stationary plate 412.Thus, for example, if the web V is moved along the pile seal 442, it ispossible to peel the web V from the pile seal 442.

Moreover, a configuration, in which a roller disposed so as to face themesh belt 46 and capable of abutting against the web V, and a seal unit(for example, pile seal) disposed on the pipe 7 side and coming intocontact with an outer peripheral surface of the roller are provided, andthe web V and a subdivided body 11 are prevented from scattering to theoutside of the pipe 7, may be provided instead of the configuration inwhich the pipe 7 is connected to the cover unit 440. In this case, thestationary plate 412 may be disposed so as to peel the web V adhered tothe roller.

2.2.2. Second Modification Example

Next, a sheet manufacturing apparatus according to a second modificationexample of the second embodiment will be described with reference to thedrawing. FIG. 9 is a view schematically illustrating a sheetmanufacturing apparatus 500 according to the second modification exampleof the second embodiment and is an enlarged view of a region including arotary body 110. Hereinafter, in the sheet manufacturing apparatus 500,points different from the examples of the above-described sheetmanufacturing apparatuses 100 and 300 will be described and descriptionof the same points will be omitted.

As illustrated in FIG. 7, in the sheet manufacturing apparatus 300, thepeeling unit 310 has the stationary plate 312. On the other hand, asillustrated in FIG. 9, in the sheet manufacturing apparatus 500, apeeling unit 310 has an airflow generation unit 512. In the illustratedexample, the peeling unit 310 is configured of the airflow generationunit 512.

The airflow generation unit 512 generates an airflow A in a direction inwhich a web V is separated from a mesh belt 46. The airflow generationunit 512 generates the airflow A in the vicinity of the rotary body 110.Here, “airflow generation unit 512 generates the airflow A in thevicinity of the rotary body 110” means the airflow A generated by theairflow generation unit 512 reaches the rotary body 110. Specifically, adistance between the airflow generation unit 512 and a base unit 112 ofthe rotary body 110 is equal to or greater than 0.1 mm and equal to orless than 0.5 mm. In the illustrated example, the airflow generationunit 512 is provided on the inside of the mesh belt 46 and faces therotary body 110 via the mesh belt 46.

In the sheet manufacturing apparatus 500, a part of the web V is peeledfrom the mesh belt 46 by the airflow A generated by the airflowgeneration unit 512 and the peeled web V can be divided by a protrusionunit 114 of the rotary body 110.

Moreover, in the above description, the airflow generation unit 512 isdescribed as an example in which the airflow A is generated by blowingair, but the airflow generation unit 512 may generate the airflow A bysuctioning air. In this case, the airflow generation unit 512 isprovided on the outside of the mesh belt 46. As the airflow generationunit 512, for example, a fan or a blower can be used.

As described above, the sheet manufacturing apparatus 500 has theairflow generation unit 512. Thus, in the sheet manufacturing apparatus500, it is possible to reliably peel the web V from the mesh belt 46.Furthermore, in the sheet manufacturing apparatus 500, for example, itis possible to transport a subdivided body 11 to the mixing unit 50 bythe airflow A.

3. Third Embodiment

3.1. Sheet Manufacturing Apparatus

Next, a sheet manufacturing apparatus according to a third embodimentwill be described with reference to the drawings. FIGS. 10 and 11 areviews schematically illustrating a sheet manufacturing apparatus 600according to the third embodiment. Hereinafter, in the sheetmanufacturing apparatus 600, points different from the example of theabove-described sheet manufacturing apparatus 100 will be described anddescription of the same points will be omitted.

As illustrated in FIGS. 10 and 11, the sheet manufacturing apparatus 600is different from the sheet manufacturing apparatus 100 described abovein that an airflow generation unit 800 configuring the peeling unit 310and a suction unit configuring a dividing unit 180 (blower 56 in thepresent embodiment) are provided.

The airflow generation unit 800 generates an airflow. Accordingly, aportion of the web V is peeled from the deposition surface of the meshbelt 46 by the airflow. Since the web V can be peeled from thedeposition surface without coming into contact with the mesh belt 46, itis possible to suppress a load to the mesh belt 46. In addition, byapplying the airflow to the mesh belt 46, it is possible to easily peelthe defibrated materials which are entangled to the mesh of the meshbelt 46 (compared to the stationary plate 312). The airflow generationunit 800 includes a blower 810, a pipe 815 of which an end is connectedto the blower 810, and a blowing unit 820 which is connected to theother end of the pipe 815. The blower 810 generates an airflow forpeeling the web V. The blowing unit 820 includes an opening portion 821.The airflow generated by the blower 810 is discharged from the openingportion 821 of the blowing unit 820 through the pipe 815.

FIG. 12 is a view schematically illustrating a blowing unit of anairflow generation unit according to the present embodiment. Asillustrated in FIG. 12, the opening portion 821 of the blowing unit 820is formed in a rectangular slit shape. In addition, the blowing unit 820is formed such that the opening area of the cross section in a directioncrossing an airflow direction (direction parallel to the opening portion821) is gradually reduced from the end portion side which is connectedto the pipe 815 toward the opening portion 821. Accordingly, it ispossible to increase a speed of the airflow which is discharged from theopening portion 821. The length of the opening portion 821 in alongitudinal direction is approximately the same as the width (length ina direction orthogonal to the transporting direction of the web V) ofthe mesh belt 46.

The shape of the blowing unit 820 is not limited to the above-describedconfiguration. FIGS. 13 and 14 are views schematically illustrating anexample of other shapes of the blowing unit of an airflow generationunit. As illustrated in FIG. 13, a blowing unit 820 a includes aplurality of nozzles 822 which are arranged in a line in a widthdirection of the mesh belt 46. The airflow generated by the blower 810is discharged from the nozzles 822 of the blowing unit 820 a through apipe 815.

In addition, as illustrated in FIG. 14, in a blowing unit 820 b, aplurality of partition walls 825 partitioning the internal space and theopening portion 821 of the blowing unit 820 b in a width direction ofthe mesh belt 46 is provided. For example, at least a part of thepartition walls 825 is formed by a filter, a mesh, or the like.Accordingly, it is configured so as to allow air to pass therethrough.In any of the space portions partitioned by the partition walls 825, apipe 815 a for introducing an airflow generated by the blower 810 isprovided. In the example illustrated in FIG. 14, the blowing unit 820 bis partitioned into five space portions by the four partition walls 825.Pipes 815 a are provided in the two space portions (each of secondportions from both the end portions) among them. The opening portion 821is divided into opening portions 821 a corresponding to the spaceportions in which the pipes 815 a are provided and opening portions 821b corresponding to the space portions in which the pipes 815 a are notprovided. Airflows flown from the pipes 815 a are directly dischargedfrom the opening portions 821 a, and airflows flown from the pipes 815 aand then passed through the partition walls 825 are discharged from theopening portions 821 b. Accordingly, the flow rate of the airflowsdischarged from the opening portions 821 b becomes lower (intensitybecomes weak) compared to the flow rate of the airflow discharged fromthe opening portions 821 a. Therefore, the intensity difference betweenthe airflows occurs in a width direction of the mesh belt 46 (widthdirection of the web V). Accordingly, the web V can be easily divided ina direction approximately parallel to the transporting direction of theweb V.

In addition, as illustrated in FIG. 11, the airflow generation unit 800is set so as to apply an airflow to the deposition surface at an acuteangle. An angle θa formed of a direction of the airflow discharged fromthe opening portion 821 and the deposition surface of the mesh belt 46applied to the tension roller 47 a is 0° or greater and less than 90°,and more preferably 0° to 60°. Accordingly, the web V deposited to themesh belt 46 can be efficiently peeled from the deposition surface.

In addition, in the present embodiment, the moisture content of theairflow applied to the mesh belt 46 by the airflow generation unit 800is adjusted. The airflow generation unit 800 includes amoisture-adjusting unit 880. The moisture-adjusting unit 880 isconnected to the pipe 815 in which the airflow from the blower 810 issent to the blowing unit 820, through a pipe 881. The moisture-adjustingunit 880 can adjust the humidity of the airflow generated by the blower810 by releasing the humidity (moisture) into the air. The relativehumidity of the airflow is adjusted, for example, at a range of 50% to70%. The airflow of which the humidity is adjusted is discharged fromthe opening portion 821 of the blowing unit 820 and then applied to thedeposition surface of the mesh belt 46 or the web V. Accordingly,electrostatic charges of the web V and the mesh belt 46 are suppressed.The web V can be easily peeled from the mesh belt 46. Themoisture-adjusting unit 880 may be a humidifying unit which increasesthe humidity.

The blower 56 configuring the suction unit is divided by suction of theweb V and forms the subdivided bodies 11. That is, the blower 56generates an airflow for suction of the peeled web V. The speed of theairflow generated by the blower 56 is set to be faster than the movingspeed of the mesh belt 46 (transporting speed of the web V). Forexample, the speed of the airflow generated by the blower 56 is set tobe 10 times or more faster than the moving speed of the mesh belt 46.Accordingly, by the speed difference between the speed of the airflowgenerated by the blower 56 and the moving speed of the mesh belt 46, theweb V is torn along the width direction of the web V (directionintersecting a transporting direction of the web V), and the torn web Vbecomes the subdivided bodies 11. The subdivided bodies 11 aretransported to the blower 56 (deposition unit 60) side by the airflow.

In addition, the dividing unit 180 includes a suction port unit 900which is connected to the blower 56. The suction port unit 900 has asuction port 921 for suction (inhaling) of the subdivided bodies 11 bythe airflow generated by the blower 56. The suction port 921 is providedin a position corresponding to the downstream side end of the web V in atransporting direction. For example, the suction port 921 is arranged soas to face the tension roller 47 a and a rotary roller 49 on thedownstream side of the tension roller 47 a and the rotary roller 49. Thesuction port unit 900 is connected to the pipe 7, the pipe 7 isconnected to the pipe 54, and the pipe 54 is connected to the blower 56.The suction port unit 900 is arranged so as to be downward inclined fromthe suction port 921 to the pipe 7, and the pipe 7 is arranged so as tobe downward inclined to the pipe 54. The subdivided bodies 11 are suckedfrom the suction port unit 900 by the airflow generated by the blower 56and are transported to the deposition unit 60 side through the pipe 7and the pipe 54.

FIG. 15 is a view schematically illustrating a suction port unit of adividing unit according to the present embodiment. As illustrated inFIG. 15, the suction port unit 900 includes a suction port 921 which isopened. The suction port 921 is formed in a rectangular slit shape. Thesuction port unit 900 is formed such that the opening area of the crosssection in a direction crossing an airflow direction (direction parallelto the suction port 921) is gradually reduced from the suction port 921toward the pipe 7. Accordingly, it is possible to increase the speed ofthe airflow toward the pipe 7. The suction port 921 has a size allowingthe subdivided bodies 11 to be sucked, and the length of thelongitudinal direction is approximately the same as the width of themesh belt 46.

The shape of the suction port unit 900 is not limited to theabove-described configuration. FIGS. 16 and 17 are views schematicallyillustrating an example of other shapes of the suction port unit of adividing unit. As illustrated in FIG. 16, in a suction port unit 900 a,a plurality of partition walls 925 partitioning the suction port 921 ina width direction of the mesh belt 46 is provided. The partition walls925 have, for example, a thin planar shape. In the example illustratedin FIG. 16, four suction ports 921 a are formed by three partition walls925. The web V peeled from the deposition surface of the mesh belt 46 bythe airflow generated by the airflow generation unit 800 is sucked anddivided by the airflow generated by the blower 56, and the divided web Vbecomes the subdivided bodies 11. When the subdivided bodies 11 (web V)are sucked in the suction port 921, the web V comes into contact withthe front end portion (front edge portion) of the partition walls 925and is divided in a direction approximately parallel to the transportingdirection (suction direction) of the web V. The web V becomes thesubdivided bodies 11 having a smaller volume, and is transported to thedeposition unit 60 side.

In addition, as illustrated in FIG. 17, a plurality of pipes 7 a isconnected to the suction port unit 900 b. In the example illustrated inFIG. 17, three pipes 7 a are provided in an equal interval. Theplurality of pipes 7 a are joined and connected to one pipe 54. Thesubdivided bodies 11 (web V) sucked from the suction port 921 are suckedin each pipe 7 a, and divided in a direction approximately parallel tothe transporting direction (suction direction) of the web V.

In addition, as illustrated in FIG. 11, the first web forming unit 45has a tension roller 47 a which is used as a supporting unit supportingthe mesh belt 46 having a deposition surface and a rotary roller 49facing the tension roller 47 a across the mesh belts 46. The rotaryroller 49 is arranged so as to come into contact with a sealing unit 991which is provided in a wall portion 990 disposed on the upper side ofthe suction port unit 900. Accordingly, the vicinity of the suction port921 is substantially sealed. The web V deposited in the depositionsurface of the mesh belt 46 is nipped by the tension roller 47 a and therotary roller 49 through the mesh belt 46. In addition, the airflowgeneration unit 800 configuring the peeling unit 310 applies the airflowgenerated by the blower 810 to the deposition surface of the mesh belt46 on a further downstream side of the web V further in a transportingdirection than the tension roller 47 a, and peels the web V from thedeposition surface. Since the web V is nipped by the tension roller 47 aand the rotary roller 49, the web V in the further downstream sideportion of a transporting direction of the web V than the nippedposition can be peeled. That is, the position where the web V is peeledfrom the deposition surface of the mesh belt 46 is stabilized, and theamount (length) of the peeled web V becomes uniform. The blower 56configuring the dividing unit 180 suctions the peeled web V and dividesthe sucked web V, and forms the subdivided bodies 11. Accordingly, thevariation of the volume of the subdivided bodies 11 transported to thedeposition unit 60 can be reduced.

In addition, in the sheet manufacturing apparatus 600 according to thepresent embodiment, an air volume caused by the blower 56 is set so asto be greater than the air volume caused by the airflow generation unit800. A first flow velocity sensor 840 for measuring the flow velocity ofthe airflow by the airflow generation unit 800 and a second flowvelocity sensor 940 for measuring the flow velocity of the airflow bythe blower 56 are provided. In the present embodiment, the first flowvelocity sensor 840 is disposed in a blowing unit 820, and the secondflow velocity sensor 940 is disposed in the suction port unit 900. Thefirst flow velocity sensor 840 and the second flow velocity sensor 940can be applied to, for example, a hot-wire flow velocity sensor. Thesensor is not limited to the hot-wire flow velocity sensor and, forexample, the sensor is applied to various flow velocity sensors whichuse a vane-type (Biram's) flow meter, a laser beam, a ultrasonic wave,or a microwave.

The first and second flow velocity sensors 840 and 940 are connected tothe control unit 140. In the control unit 140, the air volume caused bythe airflow in the blowing unit 820 and the air volume caused by theairflow in the suction port unit 900 are calculated based on measuringdata by the first and second flow velocity sensors 840 and 940. Theblower 810 and the blower 56 are controlled so that the air volumecaused by the blower 56 is set to be greater than the air volume causedby the airflow generation unit 800 compared to the air volume of theboth airflows. Specifically, a driving motor of the blower 810 or adriving motor of the blower 56 is controlled. Accordingly, dispersion orthe like of the defibrated materials by the airflow discharged from theblowing unit 820 is suppressed, and the subdivided bodies 11 can besucked in the suction port unit 900. Since the basic configuration ofthe control unit 140 is the same as the configuration of the firstembodiment, the description thereof will be omitted.

According to the above-mentioned embodiments, the following effects canbe obtained.

The first screened material passing through the opening of the screeningunit 40 is deposited on the mesh belt 46 to form the web V. The web V istransported to the mesh belt 46 in a state where the web V is nipped bythe tension roller 47 a and the rotary roller 49. The airflow caused bythe airflow generation unit 800 is applied to the deposition surface ofthe mesh belt 46 on a further downstream side of the web V in atransporting direction than the tension roller 47 a. Accordingly, theweb V, which is positioned on the further downstream side in thetransporting direction than the portion nipped by the tension roller 47a and the rotary roller 49, is peeled from the mesh belt 46. The suctionforce by the blower 56 acts on the peeled web V. Accordingly, the peeledweb V is divided to form the subdivided bodies 11, and is transported tothe mixing unit 50 (deposition unit 60) side. Thus, in the sheetmanufacturing apparatus 600, it is possible to suppress that theplurality of the defibrated materials are supplied to the depositionunit 60 in a state where the plurality of the defibrated materials areentangled together and then become a large lump and to suppress thatmeshes of the deposition unit 60 are clogged. Thus, in the sheetmanufacturing apparatus 600, it is possible to manufacture the sheet Shaving high uniformity in density and thickness.

4. Fourth Embodiment

4.1 Sheet Manufacturing Apparatus

Next, a sheet manufacturing apparatus according to a fourth embodimentwill be described with reference to the drawings. FIG. 18 is a viewschematically illustrating a sheet manufacturing apparatus 700 accordingto the fourth embodiment. Hereinafter, in the sheet manufacturingapparatus 700, points different from the example of the above-describedsheet manufacturing apparatus 600 will be described and description ofthe same points will be omitted.

As illustrated in FIG. 18, a sheet manufacturing apparatus 700 includesthe airflow generation unit 800 configuring the peeling unit 310, and asuction unit (blower 56 in the present embodiment) configuring thedividing unit 180, and the rotary body 110. In the present embodiment,the dividing unit 180 is different from the sheet manufacturingapparatus 600 described above in that the dividing unit 180 includes therotary body 110.

The rotary body 110 includes a protrusion unit 114 for forming thesubdivided bodies 11 by coming into contact with the web V and thendividing itself. In the present embodiment, the rotary body 110 is aninner part of the suction port unit 900, and is provided in the vicinityof the tension roller 47 a. The rotary body 110 is provided in aposition where the protrusion unit 114 can come into contact with theweb V peeled from the mesh belt 46 by the airflow generation unit 800,and a position which does not comes into contact with the mesh belt 46.The rotary body 110 is disposed in a position apart from the mesh belt46 so that the airflow discharged from the blowing unit 820 can bepassed through between the tip end portion of the protrusion unit 114and the deposition surface of the mesh belt 46.

FIG. 19 is a view schematically illustrating a rotary body according tothe present embodiment. As illustrated in FIG. 19, the rotary body 110has a base unit 112 and a planar shaped protrusion unit 114 protrudingfrom the base unit 112. In the illustrated example, the four protrusionunits 114 are provided at equal intervals. The protrusion unit 114 canrotate around the base unit 112. The base unit 112 extends to the web Vin a width direction. The length in an extension direction of the baseunit 112 of the 114 is the same as the width of the mesh belt 46. Thenumber of the protrusion units 114 is not specifically limited and maybe, for example, two.

The shape of the rotary body 110 is not limited to the above-mentionedconfiguration. FIGS. 20 and 21 are views schematically illustrating anexample of other shapes of the rotary body. As illustrated in FIG. 20,the rotary body 110 a has a base unit 112 and a protrusion unit 114 aprotruding from the base unit 112. Here, a plurality of protrusion units114 a is arranged in an extension direction of the base unit 112. Aconstant interval is provided between the adjacent protrusion units 114a. In a case of using the rotary body 110 a, since in the web V, aportion which comes into contact with the protrusion units 114 a and aportion which does not come into contact with the protrusion units 114 aoccur in the width direction of the rotary body 110 a, the web V can bedivided in a direction approximately parallel to the transportingdirection.

In addition, as illustrated in FIG. 21, a rotary body 110 b has the baseunit 112 and the protrusion unit 114 b protruding from the base unit112. Here, the plurality of protrusion units 114 b are disposed in anextension direction of the base unit 112, and the adjacent protrusionunits 114 a are disposed in positions which are shifted by an angle ofabout 90° in a rotating direction. In a case of using the rotary body110 b, since in the web V, a portion which comes into contact with theprotrusion units 114 b and a portion which does not come into contactwith the protrusion units 114 b occurs in the width direction of therotary body 110 b, the web V can be divided in a direction approximatelyparallel to the transporting direction.

The shape of the protrusion units 114, 114 a, and 114 b is not limitedto the planar shape. For example, the shape thereof may be a pin shape.Even in this case, the same effect can be obtained. In the sheetmanufacturing apparatus 700 of the present embodiment, since the web Vpeeled by the airflow is divided, the rotary body 110 can be disposed ina position separated from the mesh belt 46 compared to the sheetmanufacturing apparatus 100 of the first embodiment. Accordingly, theshape of the tip end portion of the protrusion unit 114 (114 a and 114b) of a rotary body 111 is made in a sharp blade-shaped, and the web Vcan be easily divided.

The rotating direction of the rotary body 110 can be appropriately setsuch as a discharging direction of the airflow caused by the airflowgeneration unit 800. In the present embodiment, the airflow caused bythe airflow generation unit 800 is discharged from bottom to top.Accordingly, the rotary body 110 is rotated in an arrow direction R3(clockwise direction in FIG. 18) along the discharging direction of theairflow caused by the airflow generation unit 800. Therefore, since therotating direction of the rotary body 110 does not go against thedischarging direction of the airflow caused by the airflow generationunit 800, the driving load is reduced, and the web V can be easilydivided.

In addition, in the sheet manufacturing apparatus 700 of the presentembodiment, the peripheral speed of the rotary body 110 is set to befaster than the moving speed of the mesh belt 46 (transporting speed ofthe web V). For example, each of the tension roller 47 and the rotarybody 110 is provided with a speed detection sensor for detecting therotating speed such as a rotary encoder (not illustrated). In thecontrol unit 140, by comparing the peripheral speed of the rotary body110 with the moving speed of the mesh belt 46 based on the detectiondata obtained by the speed detection sensor, the peripheral speed of therotary body 110 is set so as to be faster than the moving speed of themesh belt 46, for example, the driving motor for rotating the rotarybody 110 is controlled. For example, in a case where the moving speed ofthe mesh belt 46 is set to be in a range of 20 mm to 100 mm per second,the peripheral speed of the rotary body 110 is controlled so as to be aspeed which is two times or more the moving speed of the mesh belt.Accordingly, the web V can be more finely divided. Since the basicconfiguration of the control unit 140 is the same as the configurationof the first embodiment, the description thereof will be omitted.

According to the above-mentioned embodiments, the following effects canbe obtained.

Even in a state where an amount of the air of the blower 56 issuppressed, the subdivided bodies 11 can be formed by dividing the web Vby the rotary body 110. Accordingly, the energy consumption caused bythe blower 56 can be reduced.

In the airflow generation units 800 according to the third and fourthembodiments, the airflow is discharged toward the mesh belt 46, andpeels the web V from the mesh belt 46, but the configuration is notlimited thereto. For example, in the airflow generation unit 800, aconfiguration in which the web V is peeled from the mesh belt 46 bysuction of the air may be used. Even in this case, the same effect canbe obtained.

Moreover, the sheet S manufactured by the sheet manufacturing apparatusof the invention mainly refers to those in a sheet shape. However, thesheet S is not limited to the sheet shape and may be a board shape or aweb shape. In the present specification, the sheet is divided into paperand non-woven fabric. Paper includes aspects formed in a thin sheetshape using pulp and the waste paper as the raw material, and includesrecording paper for writing or printing, wallpaper, wrapping paper,colored paper, drawing paper, Kent paper, and the like. Since non-wovenfabric has a thickness thicker than that of paper or has strength lowerthan that of paper, the non-woven fabric includes general non-wovenfabric, fiber board, tissue paper (tissue paper for cleaning), kitchenpaper, cleaner, filter, liquid (waste ink and oil) absorption material,sound-absorbing material, thermal insulation material, cushioningmaterial, mat, and the like. Furthermore, as the raw material, plantfibers such as cellulose, chemical fibers such as polyethyleneterephthalate (PET) and polyester, and animal fibers such as wool andsilk may be included.

The invention omits a part of a configuration within a range havingfeatures and effects or may combine each embodiment and modificationexample. Moreover, the manufacturing unit 102 omits a part of aconfiguration within a range in which the sheet can be manufactured,adds another configuration, or may be replaced with a knownconfiguration.

The invention includes substantially the same configuration (forexample, the same configuration in the function, the method, and theresult or the same configuration in the object and the effect) as theconfiguration described in the embodiment. In addition, the inventionincludes configurations that replace non-essential portions of theconfiguration described in the embodiments. In addition, the inventionincludes configurations that can achieve the same operational effect orthe same object as the configuration described in the embodiments. Inaddition, the invention includes configurations that are obtained byadding known techniques to the configuration described in theembodiments.

The entire disclosure of Japanese Patent Application No. 2015-054415,filed Mar. 18, 2015 and 2016-028632, filed Feb. 18, 2016 are expresslyincorporated by reference herein.

What is claimed is:
 1. A sheet manufacturing apparatus comprising: animpeller mill which suctions and defibrates a raw material containingfiber, and discharges a defibrated material; a first sieve which has afirst net and screens the defibrated material by causing the defibratedmaterial to pass through the first net; a first belt, the defibratedmaterial which passes through the first sieve being deposited at anupper side of the first belt to form a first web; a rotary body having aprotrusion radially protruded from a rotation center, the rotary bodydividing the first web by rotation to form a subdivided body that isconfigured by the defibrated material; a second sieve which has a secondnet and refines the subdivided body by causing the subdivided body topass through the second net to screen the subdivided body; a secondbelt, a refined subdivided body which passes through the second sievebeing deposited at an upper side of the second belt to form a secondweb; and a heating roller which heats the second web from the secondbelt to form a sheet.
 2. The sheet manufacturing apparatus according toclaim 1, further comprising a plate which comes into contact with thefirst belt so that the first web is peeled from the first belt.
 3. Thesheet manufacturing apparatus according to claim 2, further comprising aplurality of tension rollers on which the first belt is stretched,wherein the plate faces one of the tension rollers, which is positionedclose to the rotary body, and comes into contact with the first belt. 4.The sheet manufacturing apparatus according to claim 1, furthercomprising a first blower that generates an airflow, wherein the firstweb is peeled from the first belt by the airflow generated by the firstblower.
 5. The sheet manufacturing apparatus according to claim 4,further comprising a pipe connected to the first blower, wherein theairflow, which is generated by the first blower, is discharged from thepipe at an acute angle to the first web.
 6. The sheet manufacturingapparatus according to claim 4, further comprising a pipe that isconnected to the first blower and discharges the airflow toward thefirst web, and a moisture adjusting unit that is connected to the pipeand adjusts humidity of the airflow.
 7. The sheet manufacturingapparatus according to claim 1, further comprising a subdividedbody-transfer blower arranged between the rotary body and the secondsieve, wherein the subdivided body-transfer blower transfers thesubdivided body from the rotary body to the second sieve.